The present invention relates to techniques for reliably creating a large number of high-speed electrical connections between two circuit assemblies. More specifically, the present invention provides a variety of techniques for establishing such connections with a high cycle life while requiring a very low externally created force to facilitate the connect-disconnect cycle.
As electronics becomes more dense, higher speed and complex, the force necessary to establish reliable connections between circuits, especially in semiconductor test systems, is becoming more and more difficult. Moreover, interconnect methods that rely on high contact forces and metal to metal abrasion lower the cycle life due to damage caused to the metal plating on the electrical contacts of the circuit assemblies. This is of particular concern with zero insertion force (ZIF) connectors and test heads used in semiconductor testers, such as the Agilent Technologies, Inc. V5400 and V5500 testers. A typical test head may have thirty-six zero insertion force connectors between the PEFPIF boards on the PE modules and the edge cards on a probe card.
Some conventional zero insertion force connector systems are plagued by electrical connectivity issues due to non-uniform force applied to each of the individual contact elements. Several conventional connector systems use flexible substrates to compensate for mechanical dimensional tolerances of the mating circuit assembly. However, the suppleness of the flexible substrate is directly related to the reciprocal of the electrical performance of the contact between the two circuit assemblies. As the electrical performance of the substrate improves, the mechanical flexibility decreases. This limits the dimensional pitch between the individual electrical contact elements.
Accordingly, there is a need for a zero insertion force printed circuit board connector system with reliable electrical connectivity and uniform force applied to individual contact elements.